All x79 mobos/i7's come with 40 PCIE lanes, and I've also noticed most X79 mobos have x16/x16/x8 for three way SLI, yet my $400 Asus x79 deluxe board only has x16/x8/x8 with three way SLI. Does that mean I have to step up to the Rampage series to get x16/x16/x8 for three way SLI? What about the Sabertooth x79?
Speaking from a practical point of view, SLi will be limited by the bandwidth of the slowest card, which will be running on x8. So 16/8/8 vs. 16/16/8, I don't think you will notice the difference.
The Sabertooth X79 is x16/x16/x8 The Rampage 4 Formula is x16/x8/x16 or x8/x8/x8/x8 The R4E is x16/x8/x16 or x16/x8/x8/x8
WTF and yet their flagship x79 series is only x16/x8/x8. I guess their standard x79 series isn't meant for gaming.
We still don't fully utilise x16 Gen 2, with Gen 3 (if nVidia have enabled it yet), you should be fine, losing 2-3% tops.